Automatic retarder control



May 8, 1951 s. A. MEREDITH 2,551,754

AUTOMATIC RETAROER CONTROL Filed Feb. 27, 1948 L 7 lll l will;

JNVENTOR.

Patented May 8, 1951 UNITED STATES PATENT OFFICE AUTOMATIC RETARDR CONTROL Samuel A. Meredith, Elmhurst, Ill.

Application February 27, 1948, Serial No. 11,481

5 Claims. l

My invention relates to the control of the speed of wheeled vehicles, and is particularly useful in connection with the automatic control of the speed of freight cars in a marshalling yard. It includes among its objects and advantages detector means for automatically controlling the operation of car retarding devices' as an eilectively accurate function of the kinetic energy of a car.

In the accompanying drawings:

Figure 1 is a side View partially in section, of a detector according to the invention;

Figure 2 is a view as in section on line 2--2 of Figure 1;

Figure 3 is an elevation of the parts shown in Figure 2, looked at from the right; and

Figure 4 is a detailed view of the series of detector contacts.

In the embodiment of the invention selected for illustration, the conventional rail I is supported by spaced rigid supports I2 and I4 which engage the rail throughout a length sufficient so that flexure of the unsupported rail portion between the supports I2 and I4 is substantially unaffected by loads carried by the rail at points beyond the supports I 2 and I4. Between the supports'l position deflection-responsive means which may advantageously be supported on a rigid base I6 integral with the supports I2 and I4. The deflection-responsive means illustrated includes displacement multiplying means and an inertia element arranged to move against increasing resistance, and a one-way connection to the inertia element so that the inertia element may coast further after the displacement initially actuating it has ceased. The multiplying lever I8 rests on a knife edge 2E! and its short arm ends' in an edge 22 bearing against the bottom of the rail I). Its long arm terminates in a short gear sector 24 meshing with a small pinion 26 on the shaft 28. The inertia element 3D is freely rotatable on the shaft 28 and may be displaced from the position of Figures 2 and 3 by a pin 32 projecting radially from a collar 34, integral with the pinion 26, which pin bears against an axially projecting pin 33 projecting from the inertia wheel 3G. The inertia wheel 3@ is biased toward the position of Figures 2 and 3 by a'weight 38.

It will be apparent that downward ilexure of the rail I8 will move the knife edge downward and cause the pin 32 to press against the pin 36 and rotate the inertia wheel in a clockwise direc'- tion. The distance through which the pin 32 will positively push the pin 36 will be directly proportional to the downward movement of the knife edge 32, but the time during which such movement will occur will depend on the speed of the wheel 40, being completed in the time it takes the wheel to move to the middle of the unsupported rail I0. 'Ihereafi'e` the knife edge 22 will move up again to vits original position between pin 36, and inertia wheel 30, in case the speed is sullicient, will continue to rotate for an additional incremerit 'of rotation which will be a function of the speed of the inertia element at the time the pin 32 stopped pushing. v

Means are provided for the electrical detection of the extent of movement of the inertia element, which means may be connected to the conventional electric 'sol'enoids for conditioning a car retarder to slow down the 'car to a predetermined extent. lv have illustrated six pairs of electrical contacts, 42, 44, 46, 48, 5U and 52, on a support 5I. A light bridging contact 54is mounted on the bottom of the weight 38. It will be apparent that actuation of the inertia element will swing the contact 54 up and that each successive contact will complete a corresponding circuit which may be employed in a conventional way to set a friction or other car retarder, As the automatic setting of such car retarders is conventional and well known in the art, this disclosure has not been encumbered with the details thereof.

have indicated a rubber bumper 55 to cushion the counterclockwise return movement of the inertia element.

To prevent such a device from throwing its inertia element beyond its desired range of operation when a ear of grossly excessive speed passes over the device, I provide relief means for the knife edge 20. The knife edge projects upwardly from a button 58 housed inside a sealed capsule comprising an upwardly facing cup Ell and a downwardly facing cup B2. A leaf spring 64 has its ends bearing on the bottom cup 5l) and its middle portion pushing up on the button 53, with s'ullcient force to prevent any displacement of the knife edge 20 during passage of a car of sufficient weight and speed to throw the inertia element 30 t'o the limit of its desired movement. But operation at higher speeds, instead of imposing egcessive' forces on the pin 35, will momentarily depress the knife edge 25B. Therefore, at speeds in excess of the maximum, the time during which the' maximum permissible force is exerted on the pin 32 will decrease progressively with increased speeds. For instance, if the equipment is' desired to handle cars moving at' speeds llp 801116 S'llh Speed QS 12 me'S p81* hOllI, car going 20 miles per hour will depress the knife edge 2i) and not throw the inertia element as far as if it had a speed of only 12 miles an hour. And a car going 40 miles an hour will only throw the inertia element 3B about half as far as one going 20 miles an hour.

In ordinary operation, the parts are designed so that the heaviest car to be handled will not quite bring the contact 5d into operative engage ment with the rst contacts t2. Therefore, even if a maximum weight wheel riti comes to rest in the position of Figure l, the retarder will remain inactive. But at maximum speed, the same dis-r placement may be completed in some such time interval as one-tenth of a second, and by the time the wheel li has gone on about ve or six times the length of the unsupported span of rail it, the inertia element will have coasted vup to contacts E2 and the retarder will be set for maximum action when the wheel It@ arrives. A car weighing only half as much, and traveling at maximum speed, will complete its displacement in the same time interval as the heavy car, but the top speed of the inertia element will be only'half as great and contacts it will be the highest contacts reached. The ratio between the rotary moment of inertia of the element 39, and that of the biasing weight 38 may be varied to secure any desired periodicity of swing.

Others may readily adapt the invention for use under various conditions of service by employing one or more of the novel features disclosed or equivalents thereof. With respect to the flexure of the beam lll, it will be apparent that a greater degree of uniformity of response as well as a greater degree of freedom in design with respect to the flexibility of the load-carrying span can be secured by inserting a short beam between two standard lengths of rail, which beam will preferably be a simple beam supported at its ends. With respect to the restoring force, it will be obvious that the restoring force of the weight 38 varies as the sine of the angular displacement from the vertical. It will be obvious that varying degrees of sensitivity throughout the operative range may be obtained by substituting a force directly proportional to the angular displacement, such as anordinary spiral spring, or a constant force such as a flexible tension inember encircling the wheel and lifting a constant weight. With respect to the response, the contacts illustrated provide for step by step action. Obviously various known Selsyn devices might be employed to secure greater refinement in this respect. For instance, a simple follow-up servomotor connection such that when the contact 513 rst touches the contacts d2 the contacts Zand the braking device are simultaneously moved so that the contacts 42 mcve up in front of the Contact 54 to the limit of its motion, would eliminate any step by step irregularities in the setting of the braking instrumentality. Similarly, electronic means for detecting the extent of movement of the inertia member would eliminate even the slight friction of the contact 54, and render the functioning a little more precise.

As at present advised with respect to the apparent scope of my invention, I desire to claim the following subject matter:

l. In a device of the class described, in combination: yieldable weight-sensitive means in the nature of an unsupported rail section arranged to be displaced downwardly by flexure by the downward pressure of a wheel or the like rolling over the same; an inertia element biased toward a predetermined position with a force increasing as a non-linear function of displacement; a thrust connection operative in one sense only between said weightnsensitive means and said inertia element; said thrust connection including motion multiplying mechanism; and detector means in the nature of a series of electrical contacts for detecting the extent of movement of said inertia element; whereby conventional retarding means `may be automatically controlled as a function of the energy of the load passing over; said thrust transmission including means adapted to yield at a predetermined maximum load without displacing said inertia element, to absorb displacements of excessive rapidity without iin-posing excessive load on said transmission, or excessive speed on said element.

2. In a device of the class described, in combination: yieldable weight-sensitive means in the nature of an unsupported rail section arranged to be displaced by the pressure of a wheel or the like rolling over the same; an inertia element biased toward a predetermined position with a force increasing as a function of displacement; a thrust connection operative in one sense only between said weight-sensitive means and said inertia element; said thrust connection including motion multiplying mechanism; and detector means in the nature of a series of electrical contacts for detecting the extent of movement of said inertia element; whereby conventional retarding means may be automatically controlled as a function of the energy of the load passing over; said thrust transmission including means adapted to yield at a predetermined load without displacing said inertia element, to absorb displacements of excessive rapidity without imposing excessive load on said transmission or excessive speed on said element.

3. In a device of the class described, in combination: yieldable weight-sensitive means in the nature of an unsupported rail section arranged to be displaced by the pressure of a wheel or the like rolling over the same; an inertia element biased toward a predetermined position with a force increasing as a function of displacement; a thrust connection operative in one direction only between said weight-sensitive means and said inertia element; and detector means in the nature of a series of electrical contacts for detecting the extent of movement of said inertia element; whereby conventional retarding means may be automatically controlled as a function of the energy of the load passing over; said thrust transmission including means for automatically limiting the maximum force applied to said inertia element, whereby displacement of said weight-sensitive means with excessive speed reduces the response of said inertia element. f

4. Means for securing an integrated response depending on both the weight and velocity of a moving wheeled vehicle comprising, in combination: a weight-carrying member positioned to bear the weight of a wheel passing over it; a support for said member permitting deflection ofy said member proportional to the imposed weight; a response-indicating element; restoring means yieldingly urging said element toward a predetermined position; and a transmission from said member to said element; said transmission being operative in one direction only to displace said element positively away from said predetermined position, leaving said element free to coast beyond its positive displacement due to its own kinetic energy to the extent that its kinetic k REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 466,519 White Jan. 5, 1892 923,185 Jurgensen June 1, 1909 1,037,871 Cook Sept. 10, 1912 2,071,256 Dobbs Feb. 16, 1937 

